A label-free aptasensor for fluorescent detection of carbendazim based on a G-quadruplex-specific probe

Detection of carbendazim (CZ) fungicide residues in food has received increasing attention in recent years. However, most reported methods are sophisticated, high cost, and low throughput. In this study, we designed a label-free fluorescent aptasensor for detecting CZ by using a G-quadruplex-specific probe. The anti-CZ aptamer could be partially complementary to the guanine (G)-rich sequence PW17 and block the formation of G-quadruplex structures, while not in the presence of CZ. The formed G-quadruplex structure in the presence of CZ could non-covalently bind to the fluorescent probe N -methyl mesoporphyrin IX (NMM) and activate its fluorescence. A linear relationship between fluorescence and CZ was obtained in the concentration range of 0.05–0.4 μM with a detection limit of 24.28 nM. This study provides a new perspective for designing label-free aptasensors. Graphical abstract